Syntax is user interface.
Programs must be written for people to read, and only incidentally for machines to execute.
| Erlang | Elixir | Meaning |
|---|---|---|
| and | NOT AVAILABLE | Logical 'and', evaluates both arguments |
| andalso | and | Logical 'and', short-circuits |
| or | NOT AVAILABLE | Logical 'or', evaluates both arguments |
| orelse | or | Logical 'or', short-circuits |
| =:= | === | A match operator |
| =/= | !== | A negative match |
| /= | != | Not equals |
| =< | <= | Less than or equals |
iex> a = 1
1
iex> a = 2
2
iex> ^a = 3
** (MatchError) no match of right hand side value: 3
defmodule Concat do
def join(a, b, sep \\ " ") do
a <> sep <> b
end
end
IO.puts Concat.join("Hello", "world") #=> Hello world
IO.puts Concat.join("Hello", "world", "_") #=> Hello_world
iex> string = "hełło"
"hełło"
iex> byte_size string
7
iex> String.length string
5
iex> ?a
97
iex> ?ł
322
iex> String.codepoints("hełło")
["h", "e", "ł", "ł", "o"]
iex> Enum.all? [:a, :b, :c], &is_atom(&1)
true
iex> Enum.map ["a", "B", "c"], &String.upcase &1
["A", "B", "C"]
iex> Enum.sort [1, 2, 3], &( &2 < &1 )
[3, 2, 1]
iex> fun = &(&1 + &2 + &3)
...> fun.(1, 2, 3)
6
~w(--source test/enum_test.exs) #=> ["--source", "test/enum_test.exs"]
defmodule My do
defmacro sigil_i(string, []) do
quote do: for(p <- String.split(unquote(string)), do: String.to_atom(p))
end
end
~i(asdf asdf) #=> [:asdf, :asdf]
iex> defmodule User do
...> defstruct name: "jose", age: 27
...> end
{:module, User,
<<70, 79, 82, ...>>, {:__struct__, 0}}
iex> %User{}
%User{name: "jose", age: 27}
iex> %User{name: "eric"}
%User{name: "eric", age: 27}
File.read("hello.txt")
#=> {:ok, "World"}
File.read("invalid.txt")
#=> {:error, :enoent}
File.read!("hello.txt")
#=> "World"
File.read!("invalid.txt")
#=> ** (File.Error) could not read file invalid.txt: no such file or directory
prepare_filing(sales_tax(Orders.for_customers(DB.find_customers), 2013))
DB.find_customers
|> Orders.for_customers
|> sales_tax(2013)
|> prepare_filing
defmodule Foo do
defmodule Bar do
end
end
defmodule Foo.Bar do
end
iex> for x <- [1, 2, 3, 4, 5], do: x * x
[1, 4, 9, 16, 25]
iex> for x <- [1, 2, 3, 4, 5], x < 4, do: x * x
[1, 4, 9]
iex> for x <- [1, 2], y <- [5, 6], do: x * y
[5, 6, 10, 12]
iex> for x <- [1, 2], y <- [5, 6], do: {x, y}
[{1, 5}, {1, 6}, {2, 5}, {2, 6}]
iex> Enum.map(1..10_000_000, &(&1*&1)) |> Enum.take(5)
[1, 4, 9, 16, 25]
iex> Stream.map(1..10_000_000, &(&1*&1)) |> Enum.take(5)
[1, 4, 9, 16, 25]
iex> Stream.iterate(2, &(&1*2)) |> Enum.take(10)
[2, 4, 8, 16, 32, 64, 128, 256, 512, 1024]
iex> Stream.unfold({0,1}, fn {f1,f2} -> {f1, {f2, f1+f2}} end)
...> |> Enum.take(15)
[0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233, 377]
for {codepoint, _upper, lower, _title} <- codes, lower && lower != codepoint do
defp do_downcase(unquote(codepoint) <> rest) do
unquote(:binary.bin_to_list(lower)) ++ downcase(rest)
end
end
defmodule User do
use Ecto.Model
schema "user" do
field :name
field :age, :integer
end
end
get "/pages/:page", Controllers.Pages, :show, as: :page
iex> defmodule First do
...> IO.puts "Compiling"
...> def hello_world do
...> IO.puts "Hello, world!"
...> end
...> end
Compiling
{:module, First,
<<70, 79, 82, 49, 0, 0, 7, 124, 66, 69, 65, 77, 65, 116, 111, ...>>,</70,>
{:hello_world, 0}}
Lisp isn't a language, it's a building material.
defmacro left ^^^ right do
quote do: :erlang.bxor(unquote(left), unquote(right))
end
defprotocol Inspect do
def inspect(thing, opts)
end
defimpl Inspect, for: Atom do
def inspect(false), do: "false"
def inspect(true), do: "true"
def inspect(nil), do: "nil"
end
defimpl Inspect, for: Integer do
def inspect(thing, _opts) do
integer_to_binary(thing)
end
end
defmodule MathTest do
use ExUnit.Case
test "basic operations" do
assert 1 + 1 == 2
end
end
@doc """
Checks if the given argument is nil or not.
## Examples
iex> nil?(1)
false
iex> nil?(nil)
true
"""
iex> :crypto.rand_uniform(0, 10)
3
iex> :math.pi
3.141592653589793
iex> :ets.new(:cats, [:set, :named_table])
:cats
1> 'Elixir.String':downcase(<<"ASD">>).
<<"asd">>
2> Task = 'Elixir.Task':async(fun() -> 1 + 1 end).
3> 'Elixir.Task':await(Task).
2
I think it’s pretty cool, I think we’re going to have fun together.